Virtual Surgery Planning in Orthomorphic Correction of Mandibular Dysmorphology

A new concept for mandible reconstruction after oncological resection: Multisegment virtual surgical planning

PURPOSE

Virtual surgical planning (VSP) is good for three dimensional reconstructions in maxillofacial surgery, but it is not problem-free completely especially when the resection margins cannot be affirmed in preoperative period. We aimed to obtain an ideal reconstruction with elaborating VSP to be prepared for adverse conditions during surgery and to proceed the oncological resections step- by- step with A, B, and C resection planes.

PATIENTS AND METHODS

Four patients undergoing multisegment VSP for the primary mandible malignancies were included in the study. The first resection margin was detected as plan A in VSP, and plans of B and C were also prepared considering the tumor- positive result of intraoperative frozen section procedure.

RESULTS

Following the tumor resection, margins were extended to the plan B in two patients, and plan C in one patient in accordance with the results of the frozen section procedure.Histogram comparison of the localizations of osteotomies in mandible and fibula, and positions of the implants were calculated at a confidence level of 95 % (p > 0.95) and mean difference was found -0.55 mm, while standard deviation was 1.76 mm.

CONCLUSION

Multisegment virtual surgical planning seems to achieve the optimal reconstruction with the staged resection preventing redundant removal of tumor- free structures like bone and teeth.

Osteotomy training for dental students using three-dimensional simulation software and maxillofacial three-dimensional-printed models

PURPOSE/OBJECTIVES

Simulated educational models of teeth, bones, and gums have been used for a long time in procedural skills training in dentistry.  The advent of three-dimensional (3D) printing technologies and additive manufacturing has facilitated the production of more advanced 3D printed models that can be utilized for surgical and dental training together with other technologies (e.g., 3D scanners and image analysis software).

METHODS

We conducted training on osteotomy in the maxilla and mandible using maxillofacial simulation software (MSS) and a 3D-printed model for 5th-year undergraduate dental students (13 students in 2017 and 11 students in 2018 with more than half of their results). We compared the group (13 students) who performed osteotomy after participating in the simulation lecture with those (11 students) who performed osteotomy after performing self-simulation (they were instructed to bring their personal computers and install the MSS) using tests and questionnaires (pre- and post-curriculum).

RESULTS

The average test score was significantly higher in the group who performed osteotomy using the 3D-printed model after performing self-simulation; participants in this group had acquired a better understanding of the surgical procedure. Comparison using questionnaires showed a significant difference in the students' understanding of instruments and surgical techniques between both groups.

CONCLUSION

The MSS and 3D printed models are widely used clinically. Incorporating these in the curriculum will help accelerate student development. In addition, prompt education on the purpose and usefulness of these tools will not only facilitate simulation software and 3D-printed model-based treatment plan in the clinic but also promote further research.

Pushing the Limits in Extremity Reconstruction Using Virtual Surgical Planning: A Case Series Study

SUMMARY

Technology is advancing in benefit to solving complex problems. Preoperative planning is essential in any reconstructive process given the importance of achieving good results. New technologies facilitate the process to anticipate intraoperative findings. Virtual surgical planning has contributed in the evolution of craniomaxillofacial surgery. However, limited reports have been published regarding its usefulness in extremity reconstruction. The aim of this study was to push the limits and evaluate the use of virtual surgical planning with three-dimensional images for reconstruction of complex extremity defects using a free, open-source software. Patient candidates for upper or lower extremity microsurgical reconstruction with multiple defects or defects requiring reconstruction of various tissue components were included. Computed tomography angiography images were analyzed for virtual surgical planning using Horos software (Horos, Annapolis, Md.). Two upper and eight lower extremities were reconstructed with free flaps using virtual surgical planning; six cases had multiple defects, and four cases underwent different tissue components reconstruction. The postoperative period was uneventful, and there was no flap failure. A didactic video of the process and examples of some cases are presented. Virtual surgical planning is a powerful planning method, and the authors propose its use in complex extremity defects reconstruction.

CLINICAL QUESTION/LEVEL OF EVIDENCE

Therapeutic, IV.

Traditional Versus Virtual Surgery Planning of the Fronto-Orbital Unit in Anterior Cranial Vault Remodeling Surgery

BACKGROUND

Craniosynostosis correction surgery is a complex procedure, which involves complete dismantling and reassembly of the cranial vault components. The traditional planning method for these surgeries results in increased intra-operative time owing to its highly subjective nature. The advent of virtual surgical planning (VSP) platform has lead to a greater pre-operative insight and precision outcome in calvarial remodeling surgeries. The purpose of this paper is to evaluate intra-operative time and blood loss difference as a measure of surgical efficiency between VSP based template guided Anterior Cranial Vault Reconstruction (ACVR) with Fronto-Orbital Unit Advancement (FOUA) and the traditional surgeries.

METHODS

Data were collected from patients who underwent ACVR with FOUA in our unit. Patients were divided into 2 groups, Template Fronto-Orbital Unit (TFOU) group and Non-template Fronto-Orbital Unit (NFOU) group. In TFOU group, Virtual planning along with fabrication of Template guide was carried out. Patients undergoing ACVR using traditional techniques were categorized as NFOU group. A comparative prospective analysis was carried out in terms of Intra-operative time duration and blood loss. Student 't' test was used to compare the means of the 2 groups.

RESULTS

A total of 10 patients were included in the present study. There were 5 control (NFOU) and 5 TFOU cases. There was a significant decrease in the operating time in TFOU group compared to the NFOU group. TFOU group also showed reduced intra-operative bleed compared to the NFOU group.

CONCLUSION

Virtual surgical planning (VSP) and 3D modeling with prefabricated template guide augurs reliable outcomes and portends the possibility of lesser intra-operative time. It is a valuable tool, which offers enormous benefits in terms of precise pre-surgical planning with predictive results.

Virtual Surgical Planning: The Pearls and Pitfalls

Objective

Over the past few years, virtual surgical planning (VSP) has evolved into a useful tool for the craniofacial surgeon. Virtual planning and computer-aided design and manufacturing (CAD/CAM) may assist in orthognathic, cranio-orbital, traumatic, and microsurgery of the craniofacial skeleton. Despite its increasing popularity, little emphasis has been placed on the learning curve.

Methods

A retrospective analysis of consecutive virtual surgeries was done from July 2012 to October 2016 at the University of Montreal Teaching Hospitals. Orthognathic surgeries and free vascularized bone flap surgeries were included in the analysis.

Results

Fifty-four virtual surgeries were done in the time period analyzed. Forty-six orthognathic surgeries and 8 free bone transfers were done. An analysis of errors was done. Eighty-five percentage of the orthognathic virtual plans were adhered to completely, 4% of the plans were abandoned, and 11% were partially adhered to. Seventy-five percentage of the virtual surgeries for free tissue transfers were adhered to, whereas 25% were partially adhered to. The reasons for abandoning the plans were (1) poor communication between surgeon and engineer, (2) poor appreciation for condyle placement on preoperative scans, (3) soft-tissue impedance to bony movement, (4) rapid tumor progression, (5) poor preoperative assessment of anatomy.

Conclusion

Virtual surgical planning is a useful tool for craniofacial surgery but has inherent issues that the surgeon must be aware of. With time and experience, these surgical plans can be used as powerful adjuvants to good clinical judgement.